Tuesday Morning Brings an "Inside Slider" Storm

Posted December 10, 2007, 6:29 PM.

An infrequent storm from the east, termed an "inside slider", could bring cold temperatures, gusty winds, some clouds, perhaps a shower or two and an outside chance at more Tuesday.

Winds from a cold low pressure system over the lower Colorado River are predicted to blow clouds westward over the inland valleys. The chance of measurable rainfall has been set at 20% on Tuesday. Forecasts are currently suggesting that there is not much moisture in the storm.

The right combination of events, including convection from thunderstorms, could bring low elevation snowfall like that seen in 2004. Convection pushes colder air higher in the atmosphere down to lower elevations, where it mixes unstably with warmer air.

Not every inside slider brings snow or even rain, however. There have been two or three occurrences since 2004 without any effects.

Ontario Weather Service, an independent local forecaster, further mentions an outside chance of low elevation snowfall and thunderstorms Tuesday morning, and also mentions the parallel to the November, 2004 pattern. The National Weather Service forecasts published Monday afternoon did not mention thunderstorms but do say that snow levels in the local mountains will be low.

The term "inside slider" comes from the track of a storm that travels southwards to the east of the local mountains, over the deserts, instead of the traditional coastal entry of most Pacific storms.